<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>用户登录</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            background-color: #663399;
            color: white;
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
            margin: 0;
        }

       .login-container {
            background-color: rgba(0, 0, 0, 0.7);
            padding: 20px;
            border-radius: 5px;
        }

        h2 {
            text-align: center;
        }

        form {
            display: flex;
            flex-direction: column;
        }

        label {
            margin-top: 10px;
        }

        input {
            margin-bottom: 15px;
            padding: 5px;
        }

        button {
            margin-top: 10px;
            padding: 5px 10px;
        }

       .error {
            color: red;
            margin-top: 10px;
        }
    </style>
</head>

<body>
    <div class="login-container">
        <h2>用户登录</h2>
        <form id="loginForm">
            <label for="username">用户名</label>
            <input type="text" id="username" required minlength="8" maxlength="20">
            <label for="password">密码</label>
            <input type="password" id="password" required minlength="8" maxlength="20">
            <button type="submit">提交</button>
            <button type="reset">重置</button>
        </form>
    </div>
</body>

</html>